The present invention pertains to an axle suspension of rigid axles for motor vehicles as they can be used predominantly in medium and heavy utility vehicles (UVs). Prior-art axle designs comprise usually a steering triangle fastened on the axle body above the rigid axle of the vehicle and a plurality: of longitudinal control arms arranged under the vehicle axle as well as additional stabilizing device. The steering triangle has two control arms, which form an angle with one another and are fastened to a central joint, on the one hand, and are connected via a guiding joint to the vehicle body, on the other hand. As is known, mostly molecular joints are used as the joints.
The housing for the differential is frequently integrated on the axle body, approximately in the middle of the axle. The fastening of the central joint of the steering triangle is then additionally arranged on this housing, so that an unusually large space must be made available for installation for the axle suspension. This is no longer acceptable in the manufacture of modern automobiles and especially in the case of low-platform vehicles.
The basic technical object of the present invention is to provide an axle suspension of rigid axles which requires a smaller space for installation than do prior-art embodiments while the stability of the vehicle is increased and it makes it at the same time possible to reduce the tendency of the vehicle to rolling and rocking.
Furthermore, it is an object of the invention to provide an axle suspension that is maintenance-friendly and that is able to be manufactured and installed in a simple manner. It is still another object of the invention to use standardized components where practical.
According to the invention, an axle suspension of rigid axles is provided on an axle body. The suspension includes a steering triangle as well as two longitudinal control arms located at spaced locations from the steering triangle, the two longitudinal control arms having different vertical positions. A stabilizing device is provided. The two control arms form an angle with one another and are fastened to a central joint and are each connected to the vehicle body via a guiding joint. The geometric axes of coordinates of the axle suspension is such that a first horizontal axis extending in the transverse direction of the vehicle and forms the central axis of the axle body at the same time. A second horizontal axis extends in the center of the vehicle and in the longitudinal direction of the vehicle and intersects the first horizontal axis at right angles. A vertical axis intersects the intersection of the two horizontal axes. The central joint of the steering triangle and/or the fastening of at least one of the longitudinal control arms are mounted on the axle body with an offset in relation to at least one of the two horizontal axes and the vertical axis.
The geometric axes of coordinates defined on the axle suspension provide a better understanding of the relationship between features of the invention. The first horizontal axis, which extends in the transverse direction of the vehicle and also forms the central axis of the axle body, and the second horizontal axis, which extends in the center of the vehicle and in the longitudinal direction of the vehicle intersect at a point M where the first horizontal axis extends at right angles to the second horizontal axis. The vertical axis intersects this crossing point M of the horizontal axes. The central joint of the steering triangle and/or the fastening of at least one of the longitudinal control arms are mounted to the rigid vehicle axle according to the present invention on the axle body with an offset from at least one of these axles.
xe2x80x9cOffsetxe2x80x9d is defined here as any deviation from the central arrangement of the central joint. However, the offset may also assume the value zero when the central joint is fastened, e.g., centrally on the axle body. However, embodiments in which a differential is present on the axle and the central joint is arranged laterally on this housing of the differential are possible as well. The central joint is now quasi in an xe2x80x9coblique position.xe2x80x9d
According to the present invention, each molecular joint comprises a cylindrical or spherical metallic inner part, whose fastening pins project from the housing on both sides.
A molecularly deformable elastomer body adhering to the two components is arranged between the housing and the inner part.
However, at least one of these two adhesive connections is able to slip through when a maximum allowable shear stress is exceeded, so that destruction of the elastomer body and consequently of the joint due to over stressing is effectively prevented from occurring. Adhesive connection is consequently. Defined according to the present invention as an adhesive, but detachable connection.
However, slide bearings or pivoting slide bearings may also be used besides the molecular joints.
To make it possible to manufacture the entire vehicle axle with a small number of individual parts and to correspondingly reduce the manufacturing and assembly efforts, it is advantageous to make the mounting flange, which receives the central joint of the steering triangle, in one piece with the axle body.
The central joint of the steering triangle is regularly connected detachably to the mounting flange.
Corresponding to another embodiment of the present invention, it is suggested that the connection between the mounting flange and the central joint be designed as a screw connection, which has, e.g., elongated holes at the fastening pins of the central joint to compensate tolerances.
The central joint and the guiding joints are preferably designed as molecular joints. They may be fastened according to various arrangements. For example, the inner part of the central joint may be fixed axially parallel to the horizontal axis on the axle body, which axis also forms the central axis of the axle body, or at least one of the joints is arranged coaxially or axially in parallel to a vertical axis on the vehicle. Furthermore, each joint may form an angle with this vertical axis when projected into a common plane.
Corresponding to another embodiment of the present invention, at least one of the joints comprises a metallic housing with a cylindrical inner jacket, a metallic inner part and an elastomer body arranged between the two. This compensates axial, radial and cardiac movements of the housing and of the inner part relative to one another by molecular deformation, and the elastomer body cooperating with the cylindrical inner jacket of the housing in the outward direction is adheringly arranged on the inner part and is axially pretensioned between sheet metal rings and has a crowned jacket surface geometry centrally all around and a fitted jacket surface geometry next to it on both sides all around in the preassembled, axially stress-free state, wherein the external diameter of the sheet metal rings has an undersize compared with the internal diameter of the inner jacket of the housing and a sliding surface on the circumference of the elastomer body, which sliding surface is formed under the axial tensioning and cooperates with the cylindrical inner jacket surface of the housing, allows a rotary movement of the inner part in the housing, so that the inner part slips through under overload.
Destruction and the associated premature failure of the joint and consequently of the vehicle axle is thus prevented from occurring in a simple manner.
However, depending on the vehicle axle characteristic to be achieved and in light of a soft spring characteristic, it is also possible to use in an axle suspension according to the present invention molecular joints whose housing is provided with a recess arranged inside the main load zone. The radial direction is to be considered to be the principal direction of loading in these molecular joints. The torsional loads as well as the possible cardiac (angular) deflections are rather unsubstantial and are hardly changed by a joint design according to the present invention. Such molecular joints have a ball piece as the inner part. A thicker rubber layer is applied between the inner wall of the housing and the ball surface due to a recess in the joint housing in the equatorial area of the ball piece. Since the rubber has damping properties, i.e., it is xe2x80x9csoft,xe2x80x9d such a joint has a softer spring characteristic at the beginning of its radially acting load. However, the more the rubber is compressed, the more strongly will it be pressed against the housing wall. The characteristic of the joint thus becomes harder with increasing radial spring travel.
The elastomer body may be a one-layer or multilayer elastomer body according to the present invention and may optionally have inserts consisting of metal or plastic.
According to the present invention, the steering triangle may be a one-part component made of plastic, fiber-reinforced plastic, magnesium, aluminum or steel, in whose mounts, which are prepared for this purpose, the molecular joints are inserted.
To better meet the mounting requirements, the control arms of the steering triangle may also have different lengths. It is thus possible, e.g., to mount the central joint laterally next to the differential.
Moreover, advantages arise in terms of mounting from the fact that at least one of the longitudinal control arms or of the control arms of the steering triangle is bent at right angles in the area of the guiding joints and/or of the central joint, so that the central longitudinal axis of the control arm or of the control arms and the central axis of the guiding joint are offset in space in relation to one another. The steering triangle may also have arc-shaped control arms, as a result of which steering triangle designs in which the angle formed by the control arms is greater than 60xc2x0 are possible.
According to the present invention, the steering triangle may also comprise two control arms connected to one another in the area of the central joint, where a two-part housing is used which receives the central joint in the form if a molecular joint. The housing parts are characterized by an assembly connection. Torsional movement of the housing parts in relation to one another is possible.
The above-mentionhed features of the present invention and the features yet to be explained below can, of course, be used not only in the specific combination indicated, but in other combinations or alone as well without going beyond the scope of the present invention.
Some exemplary embodiments of the axle suspensions of rigid axles according to the present invention will be explained in greater detail below with reference to the drawings.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.